As in a magic show, things are made to appear by a temporary conjunction of causes, circumstances and connections.
As in a visual aberration, things appear to be there, yet there is nothing.
As in a mirage, things appear but are not real.
As in an echo, things can be perceived but there is nothing there, either outside or inside.
As in a city of clouds, there is neither a dwelling nor anyone to dwell.
As in a reflection, things appear but have no reality of their own.
As in an apparition, there are all sorts of forms but they are not really there.